Snooping around the usual forum-haunts, one keeps tripping over all sorts of "TET/ TAT/ BCDR" threads of some sort.
Having started with the Oregon and Washington Back Roads movements around 2006/ 2007, it's been an ever-growing drive to
somehow catalog some continuous Adventure route across a whole country, coast-to-coast....or even a continent.

The Trans America Trail (TAT) is well established for the last few years.
The Trans Europe Trail (TET) is still very young and runs from Sweden to The Balkans/ Greece, with feeder routes from Portugal and Spain.

The Aussie version is the TAUT, a fairly ragged collection of shorter local routes in the main states of Oz, without any start or end, structure or targets... just a bucketload of GPS files to stitch your own stuff together (if you know how).
All of the above are solely GPS-based.

Some had a designated target and structure before the project even started (TAT, through the linking of many previously existing and fairly established state-based BCDR's) others came together as a riders-project on ADVrider or such (TET/TAUT) and are a collection of files downloadable from websites.

The glaring exception is Josh and his privately owned and run RemoteMoto.
The site has always been THE STANDOUT, well and logically structured, easy to handle and graphic, as well as generously bolstered by good photos of each and every track/ road/ route/ place etc.
The collection of support-info is not just stumping, it's extremely easy to use and filter as well, just click another layer of info over the top of a map and check the short pop-up description.
Sadly, RemotoMoto only covers the South Island of NZ as Josh lives in Christchurch.
His project has turned serious and commercial a few years ago... the time involved forced either a "go" or "quit".
It's also GPS-based, but he site offers such good description, base-maps and info that a transfer to paper-maps is a breeze.
Access to the site and all the files + info is NZ$99/year.

Just lately, some local members of ADVrider and EddieB's AdventureRidingNZ FB/ forum are starting to cobble a North Island BCDR-route together.
It's also a stitched-together collection of GPS files.

With all those NZ rides of the past and looking at things from a different (touring) angle as well as an ancient project-start up floating around the archives, and a significant collection of pics for support, creating an AusTouring version of a New Zealand Back Country Discovery Route (North + South), spanning from Cape Reinga in the very North to The Catlins in the very South shouldn't be all that much of a problem.

It'll make use of that old project as well and will be structured with a minimum of text to make translations into different languages a breeze.

You'll find the forum-listings slightly re-arranged to make this a bit easier to find and sort.

Main aim is to create a continuous ADV route from tip-to-tip to bypass as many highways and local traffic as possible....while seeing much more of the country than what most tourists (and many locals) will ever dream of.

Rideable on anything remotely "ADV"... from Posties to Fat Pigs. With full kit + travel gear.
Some of it will be not advisable on rental ADV-bikes, unless you're prepared to bear the consequences/ cost (check your rental contract THOROUGHLY!!)

A few stretches will be toll-roads (i.e. Rainbow Rd., or shipping across Lake Wakatipu etc).
Routes will be a mix of tar+ gravel with preference given to the more scenic route, whichever it is.
As a whole, the route will NOT be suitable to a "gravel-newbie"!!

The general orientation is north-south and routes are thought of as a generally continuous direction with side-trips or semi-loops added.
Many parts will have 2 or more "sort-of parallel" alternative routes which will be named as such.
Those options can be mixed + matched at intersecting locations to easily facilitate swapping i.e. from one side of the island to the other while still generally continuing the ride north or south.

Needless to say that the AT version will be Google-map + paper-map based.... those who want to transfer the Gmaps to GPX files or such are welcome to do so,
please post up the files, too! If there's a file-storage issue, pls let me know, I'll figure something out.

What it's NOT:

The fastest way from A->B.
The shortest way from A->B
A 3/7/10/15 day Golden-Guide to "The Best of NZ" ......or any stretch or part of the place.

I've got no idea at this stage how many weeks or months it would/ will take to ride the whole thing top-to-bottom.
YOU pick which part you want to use...when...for how long...with which bike...whatever.

All it's going to be is a ~15.000km/ 9.000mi route from top-to-bottom of UnZud by the most scenic routes and breathtaking roads and tracks. I can only hope you'll ever get the chance to ride part...or even ALL...of it. :hi